Individuals increasingly use electronic mail to communicate with one another for personal and business reasons. Unfortunately, unscrupulous individuals can use electronic mail for nefarious purposes, such as to send unwanted advertising email (e.g., SPAM) and perpetrate fraud against victims. Existing techniques for protecting legitimate email users generally rely on the blacklisting of certain terms (e.g., “porn”), where the presence of a blacklisted term in a message automatically results in the classification of the message as SPAM. Such techniques can be readily defeated by the unscrupulous individual. As one example, the unscrupulous individual may use terms that a human would recognize, such as “p0rn” or “p.o.r.n,” but might not appear on a blacklist. More sophisticated approaches are also being undertaken by unscrupulous individuals to defeat blacklisting and other protections. There therefore exists an ongoing need to protect against the victimization of legitimate email users.